Solid-state image sensing device

ABSTRACT

A solid-state image sensing device comprises: a light receiving unit for receiving light; a microlens formed above the light receiving unit; a fluorine-containing resin material layer formed on the microlens; and a transparent substrate provided over the fluorine-containing resin material layer. A resin layer adheres the fluorine-containing resin material layer and the transparent substrate.

RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.11/488,627, filed on Jul. 19, 2006, now U.S. Pat. No. 7,932,948,claiming priority from Japanese Patent Application Nos. 2005-210383,filed on Jul. 20, 2005 and 2005-333865, filed on Nov. 18, 2005, theentire contents of each of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

(a) Fields of the Invention

The present invention relates to solid-state image sensing deviceshaving a solid-state image sensing element and a transparent substratefor protecting the element, and to their fabrication methods.

(b) Description of Related Art

In a solid-state image sensing device employing a CCD (Charge CoupledDevice) and the like, the area of a photodiode serving as a lightreceiving unit has been decreasing by demands for downsizing andresolution enhancement thereof. Such a decrease in the area of the lightreceiving unit in turn degrades the light collection efficiency of thedevice. In order to make up for this degradation, a so-called microlenshas come to be developed and then put into use. This microlens istypically made of resin and disposed above the light receiving unitformed on each pixel. The microlens refracts light not coming directlyin the light receiving unit to collect the refracted light into thelight receiving unit, thereby enhancing light collection efficiency toimprove sensitivity.

FIGS. 15 and 16 show cross-sectional structures of a conventionalsolid-state image sensing device. Referring to FIG. 15, in the surfaceof a substrate 101 for a CCD-type solid-state image sensing element, arecess is provided on each pixel. At the bottom of the recess, aphotodiode 102 is provided which converts an incoming light into anelectrical signal. On the substrate 101 for the solid-state imagesensing element, a first acrylic flattening film 103 is formed whichflattens unevenness of the substrate surface. On the first acrylicflattening film 103, color filters 104 are formed to be associated withthe photodiodes 102, respectively. On the color filters 104, a secondacrylic flattening film 105 is formed which flattens unevennessgenerated due to gaps between the color filters 104. On the secondacrylic flattening film 105, microlenses 106 are formed to be associatedwith the photodiodes 102, respectively.

Referring to FIG. 16, a solid-state image sensing element 113 iscomposed of the photodiodes 102, the color filters 104, the microlenses106, and the like formed on the substrate 101 for the solid-state imagesensing element. The solid-state image sensing element 113 is mountedinside a package 112, and the top of the package 112 is covered with atransparent substrate 109. As shown in FIG. 15, inside the package 112,an air space 110 is interposed between the solid-state image sensingelement 113 and the back surface of the transparent substrate 109. Asshown in FIG. 15, when light 111 transmits through the transparentsubstrate 109 to come in the microlenses 106, reflections occur on thetop and bottom surfaces of the transparent substrate 109 and the topsurfaces of the microlenses 106.

However, rapid downsizing of the device in recent years has made itdifficult to secure sufficient sensitivity only by light collection fromthe microlenses. To overcome such a difficulty, a structure such that anantireflection film is formed on the microlenses is proposed (see PatentDocument 1: Japanese Patent No. 2719238).

(Patent Document 2)

Japanese Examined Patent Publication No. 7-54974

(Patent Document 3)

Japanese Examined Patent Publication No. 7-28014

(Patent Document 4)

Japanese Patent No. 2942369

SUMMARY OF THE INVENTION

However, even in the case where the antireflection film is formed on themicrolenses, the presence of the air space 110 between the solid-stateimage sensing element 113 and the transparent substrate 109 forprotecting the element as shown in FIGS. 15 and 16 causes the followingproblems.

Specifically, a large amount of light 111 is reflected on the interfacebetween the transparent substrate 109 and the air space 110, that is, onthe contact surface of the transparent substrate 109 with the air space110 (the surface thereof closer to the solid-state image sensing element113), which limits enhancement of the sensitivity of the solid-stateimage sensing device.

Furthermore, as shown in FIG. 16, if the air space 110 is presentbetween the transparent substrate 109 and the solid-state image sensingelement 113, dust or the like remaining inside the package 112 movesonto pixels of the solid-state image sensing element 113 during deliveryof the solid-state image sensing device. This disadvantageously changessome of conforming devices to defective ones.

Moreover, the presence of the air space 110 between the solid-stateimage sensing element 113 and the transparent substrate 109 limitsdownsizing (reduction in height) of the solid-state image sensingdevice.

In view of the foregoing, an object of the present invention is tostably provide a solid-state image sensing device having an enhancedsensitivity and a downsized dimension.

To attain the above object, a first solid-state image sensing deviceaccording to the present invention comprises: a light receiving unit forreceiving light; a microlens formed above the light receiving unit; afluorine-containing resin material layer formed on the microlens; and atransparent substrate provided over the fluorine-containing resinmaterial layer. In this device, a resin layer adheres thefluorine-containing resin material layer and the transparent substrate.

Preferably, in the first solid-state image sensing device according tothe present invention, the top surface of the fluorine-containing resinmaterial layer has a different contour from the surface of themicrolens.

Preferably, in the first solid-state image sensing device according tothe present invention, when the refractive indices of the microlens, thefluorine-containing resin material layer, the resin layer, and thetransparent substrate are set at n1, n2, n3, and n4, respectively, thefollowing relations hold: n3=(n2+n4)/2±0.2 and n1>n2.

Preferably, in the first solid-state image sensing device of the presentinvention, when the refractive indices of the microlens and thefluorine-containing resin material layer are set at n1 and n2,respectively, the following relations hold: n1>1.60 and n2<1.45.

Preferably, in the first solid-state image sensing device of the presentinvention, the resin layer has a thickness of 2 μm or greater.

A first method for fabricating a solid-state image sensing deviceaccording to the present invention comprises the steps of: forming,above a light receiving unit for receiving light, a microlens having afirst refractive index; forming, on the microlens, a fluorine-containingresin material layer having a second refractive index; forming, on thefluorine-containing resin material layer, a resin layer having a thirdrefractive index; and providing, on the resin layer, a transparentsubstrate having a fourth refractive index.

Preferably, in the first method for fabricating a solid-state imagesensing device according to the present invention, thefluorine-containing resin material layer is formed by spin coating.

Preferably, the first method for fabricating a solid-state image sensingdevice according to the present invention further comprises the step ofsubjecting the surface of the fluorine-containing resin material layerto oxygen plasma treatment.

The first solid-state image sensing device and its fabrication methodaccording to the present invention, however, have been found to have thedrawback: for the first solid-state image sensing device and itsfabrication method, it is difficult to define the thickness of the resinlayer serving as a layer for adhering the fluorine-containing resinmaterial layer and the transparent substrate. To be more specific, inthe case where adhesive is applied onto the fluorine-containing resinmaterial layer and then the transparent substrate (a transparentprotective member) is placed and pressed from above, it is difficult tocontrol the thickness of the resin layer made of the adhesive to adesired value. To overcome this drawback, the inventors have found a newapproach in which before formation of the resin layer, a spacer fordefining the thickness of the resin layer is disposed around a lightreceiving area (a pixel area).

To be more specific, a second solid-state image sensing device accordingto the present invention comprises: a plurality of light receiving unitsprovided in a predetermined region on a semiconductor substrate andreceiving light; and a transparent substrate provided over thesemiconductor substrate to cover the plurality of light receiving units.In this device, a resin layer adheres the semiconductor substrate andthe transparent substrate, and the thickness of the resin layer isdefined by the height of a spacer disposed around the predeterminedregion.

Preferably, in the second solid-state image sensing device of thepresent invention, the spacer is made of resin.

In the second solid-state image sensing device of the present invention,the spacer may be made of an inorganic material.

Preferably, in the second solid-state image sensing device of thepresent invention, the spacer is formed on the semiconductor substrateor on a flattening film lying on the semiconductor substrate.

Preferably, in the second solid-state image sensing device of thepresent invention, when the height of the spacer is set at 1₀ [μm] andthe thickness from the top surface of the semiconductor substrate to thebottom end of the spacer is set at 1₁ [μm], the relation: 1₀>10 [μm]−1₁is satisfied.

Preferably, in the second solid-state image sensing device of thepresent invention, the predetermined region is quadrangular, and thespacer is provided along at least two facing sides of the predeterminedregion.

Preferably, the second solid-state image sensing device of the presentinvention further comprises an amplifier unit arranged around thepredetermined region on the semiconductor substrate and amplifying asignal outputted from the plurality of light receiving units, the spaceris provided at least between the amplifier unit and the predeterminedregion, and the spacer is formed with an opening not to face theamplifier unit.

A second method for fabricating a solid-state image sensing deviceaccording to the present invention comprises the steps of: forming, in apredetermined region on a semiconductor substrate, a plurality of lightreceiving units for receiving light; providing a transparent substrateover the semiconductor substrate to cover the plurality of lightreceiving units; and adhering the semiconductor substrate and thetransparent substrate with a resin layer. In this method, a spacer isdisposed around the predetermined region before formation of the resinlayer, and the height of the spacer defines the thickness of the resinlayer.

Preferably, in the second method for fabricating a solid-state imagesensing device according to the present invention, the spacer is formedusing dry etching.

Preferably, in the second method for fabricating a solid-state imagesensing device according to the present invention, the spacer is formedby applying photosensitive resin and then sequentially subjecting theresin to exposure and development.

With the present invention, the resin layer is interposed between thetransparent substrate and a solid-state image sensing element composedof the light receiving unit, the microlens, the fluorine-containingresin material layer, and the like. In other words, unlike theconventional solid-state image sensing device, no air space isinterposed between the transparent substrate and the solid-state imagesensing element. Thus, the following effects can be exerted. That is tosay, the phenomenon in which during delivery of the solid-state imagesensing device, dust or the like moves from outside the solid-stateimage sensing element through the air space onto a pixel of thesolid-state image sensing element is eliminated, so that the occurrenceof defects resulting from this dust or the like can be completelyprevented. Moreover, the reflectivity of light at the interface betweenthe transparent substrate and the resin layer in the solid-state imagesensing device of the present invention can be made smaller than that atthe interface between the transparent substrate and the air space in theconventional solid-state image sensing device. Therefore, thesensitivity of the solid-state image sensing device can be enhanced. Tobe more specific, a decrease in the amount of reflected light betweenone side of the transparent substrate and the surface of the solid-stateimage sensing element can improve G-sensitivity (a wavelength of 550 nm)by about 8%. Furthermore, since the transparent substrate is directlyadhered to the solid-state image sensing element, downsizing andreduction in height of the device can be attained as compared to theconventional solid-state image sensing device.

With the present invention, since the thickness of the resin layer isdefined by the height of the spacer arranged around the area where thelight receiving units are disposed (the pixel area), the thickness ofthe resin layer can be controlled to a desired value. Thus, for example,a thickened resin layer can attenuate α-ray, so that expensive,high-purity glass for α-ray attenuation does not have to be used as thetransparent substrate. Consequently, fabrication costs can be reduced.Moreover, the spacer is provided along at least two facing sides of thepixel area in, for example, a quadrangular shape, which enablesarrangement of the transparent substrate in parallel with the pixelarea, that is, the image sensing surface. With this arrangement, inmounting the solid-state image sensing device of the present inventionin a camera or the like, components can be installed using the topsurface of the transparent substrate as the reference level. Therefore,the number of components installed between the reference level and alens decreases as compared to the case where a member serving as thereference level is attached to the back surface of the package like theconventional solid-state image sensing device (see, for example, PatentDocument 5: Japanese Unexamined Patent Publication No. 2005-51518). Thisreduces deviation of position for installing the components to improvethe accuracy of image sensing. Furthermore, the arrangement of thetransparent substrate in parallel with the pixel area, that is, theimage sensing surface can certainly prevent color moiré, shading(non-uniform brightness), or the like. Moreover, the spacer is providedbetween the amplifier unit and the pixel area, and the spacer is formedwith an opening not to face the amplifier unit. Thereby, when thetransparent substrate is adhered with an adhesive serving as the resinlayer to the fluorine-containing resin material layer, that is, to thesemiconductor substrate, the spacer can inhibit a decrease in amplifiersensitivity due to the adhesive attaching to the amplifier unit.

As can be seen from the above, the present invention relates tosolid-state image sensing devices having a solid-state image sensingelement and a transparent substrate for protecting the element, and totheir fabrication methods. When the present invention is applied to aCCD- or MOS-type image sensor or the like using a light-collectingmicrolens, or to a solid-state image sensing device to be mounted to adigital video camera, a digital still camera, a camera-equipped cellulartelephone, or the like, a downsized solid-state image sensing devicewith high sensitivity can be provided stably at low cost. Accordingly,the present invention is very useful.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a solid-state image sensing deviceaccording to a first embodiment of the present invention.

FIGS. 2A to 2F are sectional views showing process steps of a method forfabricating a solid-state image sensing device according to the firstembodiment of the present invention.

FIGS. 3A and 3B are views for illustrating the effect of improving thelight collection efficiency of the solid-state image sensing deviceaccording to the first embodiment of the present invention.

FIG. 4 is a view for illustrating the thicknesses of afluorine-containing resin material layer and a resin layer of thesolid-state image sensing device according to the first embodiment ofthe present invention.

FIG. 5 is a table showing comparison of the amount of light reaching amicrolens of the solid-state image sensing device between the firstembodiment of the present invention and a conventional example.

FIG. 6 is a table showing comparison of the sensitivity of thesolid-state image sensing device between the first embodiment of thepresent invention and the conventional example.

FIGS. 7A to 7F are sectional views showing process steps of a method forfabricating a solid-state image sensing device according to a secondembodiment of the present invention.

FIGS. 8A to 8D are sectional views showing process steps of the methodfor fabricating a solid-state image sensing device according to thesecond embodiment of the present invention.

FIG. 9 is a plan view showing an exemplary arrangement of a spacer inthe solid-state image sensing device according to the second embodimentof the present invention.

FIG. 10 is a plan view showing an exemplary arrangement of a spacer inthe solid-state image sensing device according to the second embodimentof the present invention.

FIG. 11 is a plan view showing an exemplary arrangement of a spacer inthe solid-state image sensing device according to the second embodimentof the present invention.

FIG. 12 is a block diagram showing an example of a schematic circuitstructure of a solid-state image sensing device intended to apply amodification of the second embodiment of the present invention.

FIG. 13 is a plan view showing an exemplary arrangement of a spacer in asolid-state image sensing device according to a modification of thesecond embodiment of the present invention.

FIG. 14 is a plan view showing an exemplary arrangement of a spacer in asolid-state image sensing device according to a modification of thesecond embodiment of the present invention.

FIG. 15 is a sectional view of a conventional solid-state image sensingdevice.

FIG. 16 is a sectional view of the conventional solid-state imagesensing device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Hereinafter, a solid-state image sensing device and its fabricationmethod according to a first embodiment of the present invention will bedescribed with reference to the accompanying drawings. Unless otherwisespecified, the drawings illustrate the state of the device after a waferis separated (diced) into the solid-state image sensing devices ofindividual element (chip) form.

FIG. 1 shows a cross-sectional structure of the solid-state imagesensing device according to the first embodiment. FIG. 1 concurrentlyshows how light comes in microlenses of the solid-state image sensingdevice according to the first embodiment.

Referring to FIG. 1, in the surface of a substrate 1 for a CCD-typesolid-state image sensing element, a recess is provided on each pixel.At the bottom of the recess, a photodiode 2 is provided which convertsan incoming light into an electrical signal. On the substrate 1 for thesolid-state image sensing element, a first acrylic flattening film 3 isformed which flattens unevenness of the substrate surface. On the firstacrylic flattening film 3, color filters 4 are formed to be associatedwith the photodiodes 2, respectively. On the color filters 4, a secondacrylic flattening film 5 is formed which flattens unevenness generateddue to the color filters 4. On the second acrylic flattening film 5,microlenses 6 are formed to be associated with the photodiodes 2,respectively. The photodiodes 2, the color filters 4, the microlenses 6,and the like formed on the substrate 1 for the solid-state image sensingelement constitute the solid-state image sensing element.

In the first embodiment, as the material for the microlens 6, use ismade of, for example, a styrene-based positive type photosensitiveresist using naphthoquinone diazide for a photosensitive base. Exposurewith ultraviolet light or visible light improves the transmissivity ofvisible light range in naphthoquinone diazide to 80% or more. Bysubjecting this resist to thermal treatment at 120 to 280° C., the shapeof the resist is becoming altered due to its thermoplasticity andsimultaneously becoming fixed due to its thermosetting property.Finally, the difference between the extents of their changes determinesthe shape of the microlens 6 made of this resist.

Also, as shown in FIG. 1, by spin coating or the like, a layer made of aresin material containing fluorine (referred hereinafter to as afluorine-containing resin material layer) 7 is formed to cover themicrolenses 6. The fluorine-containing resin material layer 7 issubjected to surface treatment by, for example, oxygen plasma. Over thefluorine-containing resin material layer 7, a transparent substrate 9 isprovided with a resin layer 8 interposed therebetween. The resin layer 8adheres the transparent substrate 9 and the fluorine-containing resinmaterial layer 7 lying on the solid-state image sensing element composedof the photodiodes 2, the microlenses 6, and the like. The transparentsubstrate 9 protects the solid-state image sensing element and seals theresin layer 8.

Note that as shown in FIG. 1, when light 11 transmits through thetransparent substrate 9 to come in the microlenses 6, reflections occuron the top and back surfaces of the transparent substrate 9, theinterface between the resin layer 8 and the fluorine-containing resinmaterial layer 7, and the top surfaces of the microlenses 6.

A fabrication method of the above-shown solid-state image sensing deviceaccording to the first embodiment will be described below.

FIGS. 2A to 2F are sectional views showing process steps of thefabrication method of the solid-state image sensing device according tothe first embodiment.

Referring to FIG. 2A, first, for example, acrylic resin is applied byspin coating to the whole of an uneven surface of the substrate 1 forthe solid-state image sensing element with the photodiode 2 provided oneach pixel, and then the applied resin is heated and dried, for example,at about 180 to 250° C. and for about 60 to 600 seconds, thereby formingthe first acrylic flattening film 3.

Next, as shown in FIG. 2B, on the first acrylic flattening film 3, thecolor filters 4 are formed to be associated with the photodiodes 2,respectively.

As shown in FIG. 2C, on the entire surfaces of the color filters 4, forexample, acrylic resin is applied by spin coating to fill unevennessgenerated due to the color filters 4, and then the applied resin isheated and dried, for example, at about 180 to 250° C. and for about 60to 600 seconds. In the first embodiment, such application and dry stepsare repeatedly conducted, for example, twice to eight times to form thesecond acrylic flattening film 5 with a high flatness.

As shown in FIG. 2D, to the entire surface of the second acrylicflattening film 5, for example, a styrene-based positive typephotosensitive resist is applied by spin coating to have a thickness of,for example, 0.5 μm or greater, and then the applied resist is dried,for example, at a low temperature of about 90 to 120° C. for about 10 to600 seconds. Thereafter, the resist is subjected to, for example,selective exposure with i-line at an exposure energy of 100 to 1000 mJ.After this exposure, the resulting resist is developed using, forexample, a TMAH (Tetramethyl Ammonium Hydroxide) solution to form adesired pattern made of remaining portions of the resist. Then, theremaining portions of the resist and the second acrylic flattening film5 is subjected to overall exposure with g-line or light having awavelength smaller than g-line and an exposure energy of 200 mJ orgreater, whereby the visible-light transmissivity of the remainingportions of the resist is improved to 80% or higher. Subsequently, theremaining portions of the resist are heated, for example, at anintermediate temperature of about 120 to 180° C. for about 60 to 600seconds. Thereby, both the thermoplastic and thermosetting performancesof the remaining portion of the resist can be controlled, whereby themicrolenses 6 are formed which have surfaces of a desired curvature anda predetermined refractive index (a first refractive index) n1. Themicrolenses 6 are subjected to thermal treatment, for example, at a hightemperature of about 190 to 280° C. for about 60 to 600 seconds toimprove the reliability of the microlens 6, to be more specific, thethermal resistance, the solvent resistance (the property resistant toalteration by solvent), and the like of the microlenses 6.

As shown in FIG. 2E, to the entire surface of the second acrylicflattening film 5 with the microlenses 6 provided thereon, a resinmaterial containing fluorine is applied by spin coating to have adesired thickness equal to or more than 0.1 μm. During this application,in order not to curve the surface of the applied resin material inaccordance with the curved surfaces of the microlenses 6, in otherwords, in order to provide the fluorine-containing resin material with adifferent surface contour from those of the microlenses 6, the spincoating is performed at a number of revolutions of, for example, about500 to 5000 rpm (revolution per minute). Subsequently, in order toprevent intake of bubbles in the fluorine-containing resin materialresulting from solvent bumping, the resin material is dried, forexample, at a low temperature of about 90 to 120° C. for about 10 to 600seconds. Then, to cure the fluorine-containing resin material, drying byheating is carried out, for example, at about 150 to 250° C. and about60 to 600 seconds to form the fluorine-containing resin material layer 7having a predetermined refractive index (a second refractive index) n2.

Note that in the case where there is no possibility of theabove-mentioned intake of bubbles in the fluorine-containing resinmaterial, the drying step at a low temperature (90 to 120° C.) describedabove may be omitted.

In the first embodiment, the sentence “not to curve the surface of theapplied resin material, that is, the top surface of thefluorine-containing resin material layer 7 in accordance with the curvedsurfaces of the microlenses 6” means that “to prevent the state in whichthe fluorine-containing resin material layer 7 with a uniform thicknessis formed on the entire surfaces of the microlenses 6 (see, for example,FIG. 3A)”. In other words, the sentence means that as exemplarily shownin FIG. 3B, the surface of the microlens 6 has a curved contour whilethe top surface of the fluorine-containing resin material layer 7 has acontour different from that curved contour, for example, a flat contour.

In the first embodiment, the thickness of the fluorine-containing resinmaterial layer 7 indicates the thickness D1 of the fluorine-containingresin material layer 7 vertically extending on the top point (thehighest position) of the microlens 6 as exemplarily shown in FIG. 4.Note that in FIGS. 3A, 3B, and 4, illustration of some components of thesolid-state image sensing device of the first embodiment shown in FIG. 1is deformed or omitted.

In the first embodiment, as the material for the fluorine-containingresin material layer 7, use can be made of, for example, acrylic-basedresin, olefin-based resin, silicone-based resin, or the like. However,from the viewpoint of thermal resistance, preferable use is made offluorine-containing silicone-based resin. To be more specific, asilicone-based resin material containing fluorine is used which isprovided by, for example, Toray Industries, Inc. In addition, hollowmicroparticles of silicon dioxide (SiO₂) or metal oxide having adiameter, for example, less than 400 nm may be dispersed in thefluorine-containing resin material layer 7. Such dispersion can offer amore reduced refractive index of the fluorine-containing resin materiallayer 7.

Subsequently, after formation of the fluorine-containing resin materiallayer 7, for example, plasma treatment using a gas containing oxygen isperformed on the surface of the fluorine-containing resin material layer7 for about 5 to 500 seconds. With this treatment, alkyl-denaturedsiloxane bonding (—SiO—R (R: alkyl group)) existing in the uppermostsurface of the fluorine-containing resin material layer 7 can be changedinto —SiO_(x). This results in a reliable resist application in the stepof removing, by etch back using a positive type resist, an organicmaterial layer which is provided on an electrode unit or an amplifierunit arranged outside the light receiving unit and which will becomenecessary later. Therefore, removal of the organic material layer on theelectrode unit or the amplifier unit can be conducted stably. Moreover,the resin layer 8 can be formed uniformly in a later step, and theinterface adhesion strength between the fluorine-containing resinmaterial layer 7 and the resin layer 8 after curing of the resin layer 8can be further enhanced. Consequently, a highly reliable solid-stateimage sensing device can be provided.

Next, as shown in FIG. 2F, to the fluorine-containing resin materiallayer 7 subjected to the plasma treatment, resin is applied to have athickness of 2 μm or greater, thereby forming the resin layer 8 with apredetermined refractive index (a third refractive index) n3.Subsequently, in order to protect the solid-state image sensing elementcomposed of the photodiodes 2, the color filters 4, the microlenses 6,and the like, the transparent substrate 9 with a predeterminedrefractive index (a fourth refractive index) n4 is placed on the resinlayer 8. During this process, the resin layer 8 is cured to adhere thefluorine-containing resin material layer 7 and the transparent substrate9.

In the first embodiment, the thickness of the resin layer 8 indicates,as exemplarily shown in FIG. 4, the thickness D2 of the resin layer 8vertically extending on the top point (the highest position) of themicrolens 6.

The material for the resin layer 8 is not specifically limited. In thefirst embodiment, acrylic-based resin provided by Nitto DenkoCorporation was used. However, another epoxy resin or the like may beused instead of this.

Next description will be made of a characteristic of the solid-stateimage sensing device according to the first embodiment. As illustratedabove, FIG. 15 shows how light comes in the microlens in theconventional solid-state image sensing device, while FIG. 1 shows howlight comes in the microlens in the solid-state image sensing device ofthe first embodiment.

As shown in FIG. 1, in the solid-state image sensing device of the firstembodiment, the resin layer 8 is interposed between the transparentsubstrate 9 and the solid-state image sensing element composed of thephotodiodes 2, the color filters 4, the microlenses 6, thefluorine-containing resin material layer 7, and the like. In otherwords, unlike the conventional solid-state image sensing device (seeFIG. 15), no air space is interposed between the transparent substrateand the solid-state image sensing element. Thus, the following effectscan be exerted.

That is to say, the phenomenon in which during delivery of thesolid-state image sensing device, dust or the like moves from outsidethe solid-state image sensing element through the air space onto a pixelof the solid-state image sensing element is eliminated, so that theoccurrence of defects resulting from this dust or the like can becompletely prevented. Note that in the solid-state image sensing deviceof the first embodiment shown in FIG. 1, dust or the like attaching ontothe outer surface of the transparent substrate 9 (the surface thereoffarther from the solid-state image sensing element) can be simplyremoved by a certain action such as wiping.

Moreover, the reflectivity of light at the interface between thetransparent substrate 9 and the resin layer 8 in the solid-state imagesensing device of the first embodiment can be made smaller than that atthe interface between the transparent substrate 109 and the air space110 in the conventional solid-state image sensing device. Therefore, thesensitivity of the solid-state image sensing device can be enhanced.

Furthermore, in the solid-state image sensing device of the firstembodiment, the transparent substrate 9 is directly adhered to thesolid-state image sensing element. Therefore, downsizing of the devicecan be attained as compared to the conventional solid-state imagesensing device.

To be more specific, in the first embodiment, the refractive index (thefirst refractive index) of the microlens 6 is set at n1, the refractiveindex (the second refractive index) of the fluorine-containing resinmaterial layer 7 is set at n2, the refractive index (the thirdrefractive index) of the resin layer 8 is set at n3, and the refractiveindex (the fourth refractive index) of the transparent substrate 9 isset at n4. For these settings, if n3=(n2+n4)/2±0.2 and n1>n2, the amountof light capable of passing through the microlens 6 is 98% or more ofthe amount of light coming into the transparent substrate 9, as shown inFIG. 5. In other words, the amount of light lost before the light passesthrough the microlens 6 is 2% or smaller. On the other hand, for theconventional solid-state image sensing device, the amount of light lostbefore the light passes through the microlens 106 reaches about 10%.

In the solid-state image sensing device of the first embodiment shown inFIG. 5 (the solid-state image sensing devices 1 to 3 of the presentinvention), styrene-based resin (n1=1.65) is used as the material forthe microlens 6, fluorine-containing silicone-based resin (n2=1.41) isused as the material for the fluorine-containing resin material layer 7,three types of acrylic-based resin differing in refractive index(n3=1.26, 1.46, and 1.66) are used as the material for the resin layer8, and glass (n4=1.52) is used as the material for the transparentsubstrate 9. In this embodiment, it is needless to say that othermaterials capable of satisfying the above-shown equation representingthe relation of refractive index can be used as the materials for thelisted components. The conventional solid-state image sensing device 1employed for comparison is made so that a transparent substrate(n4=1.52) similar to the transparent substrate 9 of the first embodimentis placed over microlenses similar to the microlenses 6 of the firstembodiment with the air space (n2 and n3=1) interposed therebetween. Theconventional solid-state image sensing device 2 is made so that atransparent substrate (n4=1.52) similar to the transparent substrate 9of the first embodiment is placed over microlenses similar to themicrolenses 6 of the first embodiment while a resin material layer(n2=1.41; which is provided as an antireflection film) similar to thefluorine-containing resin material layer 7 of the first embodiment andan air space (n3=1) are interposed between the microlens and thesubstrate.

If, as shown in FIGS. 5, n1>1.60 and n2<1.45, the light collectionability of the microlens 6 can be maintained sufficiently. Therefore,light passing through the microlens 6 can be efficiently guided to thephotodiode 2.

Moreover, in the first embodiment, as exemplarily shown in FIG. 3B, thetop surface of the fluorine-containing resin material layer 7 isprevented from being curved in accordance with the curved surfaces ofthe microlenses 6. With this structure, even if n2<n3 (the solid-stateimage sensing devices 2 and 3 of the present invention), light 11 can becollected efficiently into the photodiode 2. In contrast to this, in thecase where, as shown in FIG. 3A, the top surface of thefluorine-containing resin material layer 7 is curved in accordance withthe curved surfaces of the microlenses 6, if n2<n3, light 11 coming fromthe resin layer 8 into the fluorine-containing resin material layer 7disperses at the time of the incoming. As a result, the light 11 cannotbe guided efficiently to the photodiode 2. Preferably, the top surfaceof the fluorine-containing resin material layer 7 is ideally flat.However, if the unevenness of the uppermost surface of thefluorine-containing resin material layer 7 (see FIG. 4) has a differencein level of about 300 nm or the smaller, the properties of thesolid-state image sensing element as substantially identical as the casewhere the fluorine-containing resin material layer 7 is flat can beprovided.

With the above-described solid-state image sensing device of the firstembodiment (for example, “the solid-state image sensing devices 1 to 3of the present invention” shown in FIG. 5), as shown in FIG. 6, it hasbeen recognized that as compared to the conventional solid-state imagesensing device (see FIG. 15), the sensitivity of the detected voltage isimproved by about 10%.

Furthermore, with the solid-state image sensing device of the firstembodiment, vertical downsizing (reduction in height) by about 0.5 to5.0 mm can be attained as compared to the conventional solid-state imagesensing device (see FIG. 16).

In the first embodiment, since the fluorine-containing resin materiallayer 7 is formed by spin coating, the fluorine-containing resinmaterial layer 7 can be formed on the microlenses 6 before a wafer withthe solid-state image sensing elements built thereon is separated(diced) into individual solid-state image sensing elements. This offersthe following effects. That is to say, in general, the properties of thesolid-state image sensing device depend greatly on the opticalproperties of the microlenses and a layer formed immediately above.However, if the fluorine-containing resin material layer 7 can be formedbefore dicing, intermediate inspections of the individual solid-stateimage sensing elements can be carried out before the transparentsubstrates are placed over the respective solid-state image sensingelements made by dicing the wafer. Therefore, based on the results ofthe inspections, a subsequent formation of the resin layer 8 and a laterplacement of the transparent substrate 9 can be made only to conformingsolid-state image sensing elements. This greatly reduces fabricationcosts, so that the first embodiment is very useful.

Furthermore, in the first embodiment, since the thickness of the resinlayer 8 having the third refractive index n3 is set at 2 μm or more, thetotal thickness of organic material layers (the total thickness of theresin layer 8, the fluorine-containing resin material layer 7, themicrolens 6, the second acrylic flattening film 5, the color filter 4,and the first acrylic flattening film 3) through which the light 11coming from the transparent substrate 9 passes to reach the photodiode 2can be set at 5 μm or greater. Thus, α-ray coming from outside thedevice is fully absorbed in those organic material layers, so that thenecessity to subject the transparent substrate 9, that is, glass toprocessing for taking measures against α-ray is eliminated. This resultsin a further decrease in fabrication costs.

As described above, in the first embodiment, as shown in FIGS. 1, 3, and5, the amount of light reaching the microlenses 6 can be furtherincreased as compared to the amount of light in the conventionalsolid-state image sensing device, and concurrently the light 11 havingreached the microlens 6 can be efficiently guided to the photodiode 2.Therefore, a solid-state image sensing device with a high sensitivitycan be provided. Moreover, the occurrence of defects resulting from dustor the like can be prevented and a more increasing downsizing can beattained than the conventional example. Furthermore, processing fortaking measures against α-ray does not have to be taken and intermediateinspections of the solid-state image sensing element including thecomponents greatly affecting optical properties of the device can becarried out before dicing into individual devices. Therefore, adownsized solid-state image sensing device with high sensitivity can beprovided stably at low cost.

It goes without saying that exemplary applications of the presentinvention are not limited to the embodiment described above. Forexample, in the first embodiment, acrylic resin is used for theflattening films 3 and 5. However, the material for the flattening filmis not limited to acrylic resin as long as a material to be used is aheat-resistant resin with high transmissivity to visible light.

In the first embodiment, as the material for the color filter 4, use maybe made of, for example, photosensitive resist containing pigment ordye. Alternatively, the color filter 4 may be formed by etchingnon-photosensitive resist containing pigment or dye. The color ofpigment or dye to be used may be complementary color or primary color.

In the first embodiment, as the material for the microlens 6, use ismade of styrene-based positive type resist employing a derivative ofnaphthoquinone diazide for a photosensitive agent. However, the materialfor the microlens 6 is not limited to this styrene-based positive typeresist. In this regard, positive type resist used as an alternative tothis styrene-based positive type resist must satisfy the following fiveconditions: (1) good adhesion to the underlying flattening film; (2) theability to form a fine pattern by selective exposure; (3) the ability toenhance visible-light-range transmissivity by exposure to have a valueof 80% or more; (4) the ability of thermal treatment to alter the shapeof the resist due to thermoplasticity and simultaneously to fix it dueto thermosetting property, thereby determining the final shape by thedifference between the extents of their changes; and (5) goodreliability of thermal resistance, solvent resistance, and the like. Asexposure light used in the step of exposing positive type resist thatwill be the microlens 6, use may be made of ultraviolet ray or visibleray, specifically, i-line, g-line, h-line, or mixed ray of the listedray. Alternatively, ultraviolet ray having another wavelength differentfrom i-line, g-line, and h-line or electron ray may be used. Themicrolens may be formed using a pattern transfer process by etch back,or using a grayscale mask. Further, for example, metal oxide particleswith a diameter of about 400 nm or smaller may be dispersed in themicrolens 6.

Second Embodiment

Hereinafter, a solid-state image sensing device and its fabricationmethod according to a second embodiment of the present invention will bedescribed with reference to the accompanying drawings. The secondembodiment differs greatly from the first embodiment in that beforeformation of a resin layer, a spacer for defining the thickness of theresin layer is disposed around a light receiving area (a pixel area).This facilitates definition of the thickness of the resin layer servingas a layer for adhering a fluorine-containing resin material layer, thatis, a semiconductor substrate and a transparent substrate.

FIGS. 7A to 7F and 8A to 8D are sectional views showing process steps ofthe method for fabricating a solid-state image sensing device accordingto the second embodiment. Note that overlapping description of thecomponents of the solid-state image sensing device shown in FIGS. 7A to7F and 8A to 8D which are the same as those in the first embodimentshown in FIGS. 1 and 2A to 2F and the like will be omitted by retainingthe same reference numerals as the first embodiment.

Referring to FIG. 7A, first, a substrate 1 for a solid-state imagesensing element is prepared which is made of a semiconductor substrateor the like. In a predetermined pixel area of the substrate 1, aplurality of photodiodes 2 are formed on the respective pixels.Subsequently, for example, acrylic resin is applied by spin coating tothe entire surface of the substrate 1 for the solid-state image sensingelement, and then the applied resin is heated and dried, for example, atabout 180 to 250° C. and for about 60 to 600 seconds, thereby forming afirst acrylic flattening film 3.

Next, as shown in FIG. 7B, on the first acrylic flattening film 3, thecolor filters 4 are formed to be associated with the photodiodes 2,respectively.

As shown in FIG. 7C, to the entire surfaces of the substrate 1 for thesolid-state image sensing element including the top of the color filters4, for example, acrylic resin is applied by spin coating to fillunevenness generated due to the color filters 4. Then, the applied resinis heated and dried, for example, at about 180 to 250° C. and for about60 to 600 seconds. In the second embodiment, such application and drysteps are repeatedly conducted, for example, twice to eight times toform a second acrylic flattening film 5 with a high flatness.

Like the step shown in FIG. 2D of the first embodiment, as shown in FIG.7D, microlenses 6 are formed on the second acrylic flattening film 5 tobe associated with the photodiodes 2, respectively.

Like the step shown in FIG. 2E of the first embodiment, as shown in FIG.7E, a fluorine-containing resin material layer 7 is formed on the entiresurface of the second acrylic flattening film 5 with the microlenses 6provided thereon, and then like the first embodiment, the surface of thefluorine-containing resin material layer 7 is subjected to plasmatreatment.

Next, as shown in FIG. 7F, an inorganic material layer 10 of, forexample, SiN or SiO₂ is formed on the entire surface of thefluorine-containing resin material layer 7. Subsequently, as shown inFIG. 8A, a resist pattern 15 covering a spacer formation region locatedaround the pixel area is formed on the inorganic material layer 10.Thereafter, as shown in FIG. 8B, using the resist pattern 15 as a mask,the inorganic material layer 10 is dry etched with a plasma made of apredetermined etching gas. With this process, as shown in FIG. 8C, aspacer 12 is formed on a portion of the fluorine-containing resinmaterial layer 7 located around the pixel area. In this embodiment, thespacer 12 has a predetermined height for determining the thickness of aresin layer that will be described later. FIG. 9 is a plan viewexemplarily showing how the spacer 12 is arranged around a pixel area 21in a solid-state image sensing device 20 of the second embodiment.

As shown in FIG. 8D, to the fluorine-containing resin material layer 7formed with the spacer 12, resin is applied to have a thickness of, forexample, 2 μm or greater, thereby forming the resin layer 8. Then, inorder to protect the solid-state image sensing element composed of thephotodiodes 2, the color filters 4, the microlenses 6, and the like, atransparent substrate 9 is placed on the resin layer 8. During thisprocess, the resin layer 8 is cured to adhere the transparent substrate9 and the fluorine-containing resin material layer 7, that is, thesubstrate 1 for the solid-state image sensing element. The thickness ofthe resin layer 8 is defined by the height of the spacer 12.

Also in the second embodiment, like the first embodiment, the thicknessof the resin layer 8 indicates, as exemplarily shown in FIG. 4, thethickness D2 of the resin layer 8 vertically extending on the top point(the highest position) of the microlens 6.

With the second embodiment described above, the following effects can beoffered in addition to the same effects as the first embodiment. To bemore specific, since the thickness of the resin layer 8 is defined bythe height of the spacer 12 arranged around the pixel area, thethickness of the resin layer 8 can be controlled to a desired value.Thus, for example, a thickened resin layer 8 can attenuate α-ray, sothat expensive, high-purity glass for α-ray attenuation does not have tobe used as the transparent substrate 9. Consequently, fabrication costscan be reduced.

In the second embodiment, the spacer 12 is formed by using an inorganicmaterial as the material for the spacer 12 to subject the inorganicmaterial to dry etching. Instead of this, photosensitive resin or thelike may be used as the material for the spacer 12. To be more specific,the spacer 12 made of resin may be formed by applying photosensitiveresin onto the fluorine-containing resin material layer 7 and thensequentially subjecting the photosensitive resin to exposure anddevelopment. With such a procedure, the spacer 12 can be formed easilyafter completion of the solid-state image sensing element composed ofthe photodiodes 2, the color filters 4, the microlenses 6, and the like(that is, after formation of the element on the chip).

In the second embodiment, the spacer 12 is formed on thefluorine-containing resin material layer 7. Instead of this, the spacer12 may be formed on the second acrylic flattening film 5 by arranging aspacer formation region in a region where the fluorine-containing resinmaterial layer 7 is not provided, the spacer 12 may be formed on thefirst acrylic flattening film 3 by arranging a spacer formation regionin a region where the fluorine-containing resin material layer 7 and thesecond acrylic flattening film 5 are not provided, or the spacer 12 maybe formed on the substrate 1 for the solid-state image sensing elementby arranging a spacer formation region in a region where thefluorine-containing resin material layer 7, the second acrylicflattening film 5, and the first acrylic flattening film 3 are notprovided. Such a structure can arrange the spacer 12 in a locationsufficiently away from the pixel area, that is, the light-receivingsurface, so that adhesion of the transparent substrate 9 larger than thelight-receiving surface is facilitated.

In the second embodiment, the height of the spacer 12 with reference tothe top surface of the fluorine-containing resin material layer 7 is setat 1₀ [μm], and the thickness from the top surface of the substrate 1for the solid-state image sensing element, that is, from the top surfaceof the semiconductor substrate to the top surface of thefluorine-containing resin material layer 7, that is, the bottom end ofthe spacer 12 is set at 1₁ [μm]. In such a setting, it is preferable tosatisfy the relation: 1₀>10 μm−1₁. With this relation, even in the casewhere inexpensive glass poorly contributing to α-ray attenuation is usedfor the transparent substrate 9, a resin whose thickness from the topsurface of the substrate to the top surface of the resin layer 8 isgreater than 10 μm can attenuate α-ray sufficiently. As long as therelation described above is satisfied, in the case where the thickness1₁ from the top surface of the substrate to the top surface of thefluorine-containing resin material layer 7 (the bottom end of the spacer12) is more than 8 μm, the height 1₀ of the spacer 12, that is, thethickness of the resin layer 8 may be less than, for example, 2 μm.

In the second embodiment, if, for example, the plan shape of the pixelarea is set to be quadrangular, the spacer 12 is preferably providedalong at least two facing sides of the pixel area 21 of the solid-stateimage sensing device 20 of the second embodiment, as exemplarily shownin FIGS. 10 and 11. This enables arrangement of the transparentsubstrate 9 in parallel with the pixel area 21, that is, the imagesensing surface. With this arrangement, in mounting the solid-stateimage sensing device 20 of the second embodiment in a camera or thelike, components can be installed using the top surface of thetransparent substrate 9 as the reference level. Therefore, the number ofcomponents installed between the reference level and a lens decreases ascompared to the case where a member serving as the reference level isattached to the back surface of the package like the conventionalsolid-state image sensing device (see, for example, Patent Document 5:Japanese Unexamined Patent Publication No. 2005-51518). This reducesdeviation of position for installing the components to improve theaccuracy of image sensing. Furthermore, the arrangement of thetransparent substrate 9 in parallel with the pixel area 21, that is, theimage sensing surface can certainly prevent color moiré, shading(non-uniform brightness), or the like.

Modification of Second Embodiment

Hereinafter, a solid-state image sensing device and its fabricationmethod according to a modification of the second embodiment of thepresent invention will be described with reference to the accompanyingdrawings. As compared to the second embodiment, a characteristic of thismodification is that a spacer in the present invention is providedbetween a pixel area and an amplifier unit arranged around the pixelarea, and that the spacer is provided with an opening not to face theamplifier unit.

FIG. 12 exemplarily shows a schematic circuit structure of a solid-stateimage sensing device, specifically, an interline-transfer CCDsolid-state image sensing device intended to apply this modification. Asshown in FIG. 12, an image sensing region (pixel area) 63 of a CCDsolid-state image sensing device 51 is composed of a plurality of lightreceiving units (photoelectric conversion units) 61 and a plurality ofvertical transfer registers 62. The light receiving units 61 arearranged in the row direction (vertical direction) and in the columndirection (horizontal direction), that is, in matrix form, andaccumulate signal charges according to the amount of incoming light. Thevertical transfer registers 62 are arranged on vertical lines of thelight receiving units 61, respectively, and vertically transfer signalcharges read out from the light receiving units 61. In the image sensingregion 63, each of the light receiving units 61 is made of, for example,a pn junction photodiode, and each of the vertical transfer registers 62is made of a CCD. In response to application of a charge readout pulseto a readout gate (not shown), signal charges accumulated in the lightreceiving unit 61 are read out to the vertical transfer register 62. Thevertical transfer register 62 is driven for transfer by, for example,three-phase vertical transfer clocks φV1 to φV3 supplied from a drivecircuit 52. Signal charges read out to the vertical transfer register 62are vertically transferred by an amount corresponding to a singlescanning line for part of the horizontal blanking period.

As shown in FIG. 12, in a region adjacent to the image sensing region63, a first horizontal transfer register 64 and a second horizontaltransfer register 65 are arranged in parallel with each other with atransfer gate 66 interposed therebetween. To the first and secondhorizontal transfer registers 64 and 65, signal charges corresponding toa single scanning line are sequentially transferred from the pluralityof vertical transfer registers 62. The first and second horizontaltransfer registers 64 and 65 are each made of a CCD. These twohorizontal transfer registers 64 and 65 are driven for transfer bytwo-phase horizontal transfer clocks φH1 and φH2 supplied from the drivecircuit 52, whereby signal charges with an amount of two lines aresequentially transferred horizontally for a horizontal scanning periodafter the horizontal blanking period. At ends of the horizontal transferregisters 64 and 65, charge detection units 67 and 68 are disposed whichhave, for example, floating diffusion structures, respectively. Thetwo-channel signal charges having horizontally transferred aresequentially converted by the charge detection units 67 and 68 intovoltage signals. This voltage signals are amplified by output amplifiers69 and 70 which are connected to the horizontal transfer registers 64and 65 through the charge detection units 67 and 68, respectively, andthen the amplified signals are supplied from the CCD solid-state imagesensing device 51 as two-channel CCD outputs 1 and 2 according to theamount of light incoming from a subject of the image. As describedabove, the non-interlaced (progressive scan type) CCD solid-state imagesensing device 51 is constructed which is provided with the two-channelhorizontal transfer registers 64 and 65.

When this modification is targeted for a two-channel (two amplifiers)driven CCD solid-state image sensing device, as exemplary shown in FIG.13, two horizontal transfer registers 25 and two amplifier units 30connected to the horizontal transfer registers 25, respectively, aredisposed around the pixel area 21 (where, for example, light receivingunits and vertical transfer registers (not shown) are arranged) of thesolid-state image sensing device 20 of this modification. In thisdevice, the spacer 12 is provided at least between each of the amplifierunits 30 and the pixel area 21, and the spacer 12 is provided with anopening not to face each of the amplifier units 30.

When this modification is targeted for a four-channel (four amplifiers)driven CCD solid-state image sensing device, as exemplary shown in FIG.14, four horizontal transfer registers 25 and four amplifier units 30connected to the horizontal transfer registers 25, respectively, aredisposed around the pixel area 21 (where, for example, light receivingunits and vertical transfer registers (not shown) are arranged) of thesolid-state image sensing device 20 of this modification. In thisdevice, the spacer 12 is provided at least between each of the amplifierunits 30 and the pixel area 21, and the spacer 12 is provided with anopening not to face each of the amplifier units 30.

With this modification described above, the following effects can beoffered in addition to the effects of the first and second embodiments.Specifically, the spacer 12 is provided between the amplifier unit 30and the pixel area 21, and the spacer 12 is provided with an opening notto face the amplifier unit 30. Thereby, when to the fluorine-containingresin material layer 7, that is, to the substrate 1 for the solid-stateimage sensing element, the transparent substrate 9 is adhered withadhesive serving as the resin layer 8, the spacer 12 can block theadhesive applied to, for example, the pixel area 21 from being squeezedout to the amplifier unit 30. At the time of the blocking, the adhesiveare squeezed out through the spacer opening, which is arranged not toface the amplifier unit 30, to the outside of the pixel area 21 (aregion of the device where no amplifier unit 30 is arranged). Thiscertainly prevents a decrease in amplifier sensitivity (lowering ofamplifier sensitivity to about 3 to 10%) due to the adhesive attachingto the amplifier unit 30.

It goes without saying that in this modification, the drive system ofthe solid-state image sensing device is not specifically limited.

1. A solid-state image sensing device comprising: a plurality of lightreceiving units provided in a predetermined region on a semiconductorsubstrate and receiving light; and a transparent substrate provided overthe semiconductor substrate to cover the plurality of light receivingunits, wherein a resin layer adheres the semiconductor substrate and thetransparent substrate, the thickness of the resin layer is defined bythe height of a spacer disposed around the predetermined region, andwhen the height of the spacer is set at 1₀ [μm] and the thickness fromthe top surface of the semiconductor substrate to the bottom end of thespacer is set at 1₁ [μm], the relation: 1₀>10 [μm]−1₁ is satisfied. 2.The device of claim 1, wherein the spacer is made of resin.
 3. Thedevice of claim 1, wherein the spacer is made of an inorganic material.4. The device of claim 1, wherein the spacer is formed on thesemiconductor substrate or on a flattening film lying on thesemiconductor substrate.
 5. The device of claim 1, wherein thepredetermined region is quadrangular, and the spacer is provided alongat least two facing sides of the predetermined region.
 6. A solid-stateimage sensing device comprising: a plurality of light receiving unitsprovided in a predetermined region on a semiconductor substrate andreceiving light; a transparent substrate provided over the semiconductorsubstrate to cover the plurality of light receiving units, and anamplifier unit arranged around the predetermined region on thesemiconductor substrate and amplifying a signal outputted from theplurality of light receiving units, wherein a resin layer adheres thesemiconductor substrate and the transparent substrate, the thickness ofthe resin layer is defined by the height of a spacer disposed around thepredetermined region, and the spacer is formed at least between theamplifier unit and the predetermined region, and the spacer is providedwith an opening not to face the amplifier unit.
 7. The device of claim6, wherein the spacer is made of resin.
 8. The device of claim 6,wherein the spacer is made of an inorganic material.
 9. The device ofclaim 6, wherein the spacer is formed on the semiconductor substrate oron a flattening film lying on the semiconductor substrate.
 10. Thedevice of claim 6, wherein the predetermined region is quadrangular, andthe spacer is provided along at least two facing sides of thepredetermined region.